Andy Evans wrote:


Notice that LdF placed the grid on one side of the heater and the anode
on
the other side of the heater. It took him a couple of months to figure
out
that things worked better with the grid between the heater and the
anode (as
can be seen in a later LdF patent).


Interesting (and pointless) idea, with the grid like that, I expect you
would need to drive the grid positive to prevent current flow.

--
Nick